Property a and property b share a common wall along the property boundary. to ensure that neither owner destroys the wall, the owners of a and b should create: ) an easement by necessity. b) a perpetual encroachment. c) a license. d) a party wall easement.

a party wall easement.

Explanation:

A party wall is a dividing wall between two adjoining buildings that is shared by the occupants of each residence or business. A party easement however is a contract that binds both parties from the above from destroying the wall without consensual agreement, giving each party title to one half of the wall(the part facing each party's building) and some sort of coming interest in the adjoining wall.

answer; ///it examines the interaction between genetics and culture in shaping human biology;

an informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.